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PubMed1990

Force interval relationship (FIR) related to the global function of the left ventricle: a computer study.

A model which relates the left ventricular (LV) geometry, structure and sarcomere properties to its global function, recently proposed by the authors, is extended to account for contractility changes which are a function of the heart rate, prematurity of the beat and calcium transients within the cell. To characterise LV function and relate it to fibre function under varying rhythm conditions, a model of muscle force restitution, based on calcium kinetics, was used to calculate the maximum fibre stress at the optimum sarcomere length sigma o as the parameter which depends on the heart rate, the test pulse interval TPI, the action potential duration APD and the restitution time constant. The global LV force interval relationship FIR was then calculated, and by comparing the calculated FIR to the experimental measurement (in dogs) at the ventricular level, the constants of the restitution of force at the fibre level were derived. Based on these constants, the LV function under ejecting conditions at various rhythm disturbances was calculated and related to the local, distributed parameters. This approach provides a tool to describe ventricular function as well as transmural distribution of stress and sarcomere length at a wide variety of loading and rhythm conditions based on given 'muscle level' parameters.

Biomechanical Phenomena↗
PubMed1995

Use of finite wordlength FIR digital filter structures with improved magnitude and phase characteristics for reduction of muscle noise in EEG signals.

One of the main disturbances in EEG signals is EMG artefacts generated by muscle movements. In the paper, the use of a linear phase FIR digital low-pass filter with finite wordlength precision coefficients is proposed, designed using the compensation procedure, to minimise EMG artefacts in contaminated EEG signals. To make the filtering more effective, different structures are used, i.e. cascading, twicing and sharpening (apart from simple low-pass filtering) of the designed FIR filter. Modifications are proposed to twicing and sharpening structures to regain the linear phase characteristics that are lost in conventional twicing and sharpening operations. The efficacy of all these transformed filters in minimising EMG artefacts is studied, using SNR improvements as a performance measure for simulated signals. Time plots of the signals are also compared. Studies show that the modified sharpening structure is superior in performance to all other proposed methods. These algorithms have also been applied to real or recorded EMG-contaminated EEG signal. Comparison of time plots, and also the output SNR, show that the proposed modified sharpened structure works better in minimising EMG artefacts compared with other methods considered.

Artifacts↗
PubMed2005

Two classes of 5S rDNA unit arrays of the silver fir, Abies alba Mill.: structure, localization and evolution.

The structure and organization of the 5S ribosomal DNA units of the silver fir, Abies alba Mill., as well as their position in the chromosome complement were investigated. PCR amplification of the gene and nontranscribed spacer region, sequence analysis and Southern hybridization, using a homologous probe, detected DNA sequences of approximately 550 bp and 700 bp. Sequence analysis of the spacers revealed that the difference in length between the sequences occurred in the middle spacer region as a result of the amplification of a 75-bp sequence of the short unit class, which is organized in four 54- to 68-bp tandem repeats in the long spacer unit. The 5S rDNA transcribed region is 120 bp long and shows high sequence similarity with other gymnosperm species. The comparative analysis of 5' and 3' flanking sequences of 5S rRNA genes of silver fir and other gymnosperms indicates that A. alba spacer units have the same rate of evolution and are more closely related to Larix and Pseudotsuga than to Pinus and Picea. Southern hybridization and fluorescence in situ hybridization of metaphase chromosomes of A. alba suggest that the short and long spacer units are organized as separate tandem arrays at two chromosomal loci on chromosomes V and XI.

Abies↗
PubMed2002

SCAR markers to detect mycorrhizas of an American Laccaria bicolor strain inoculated in European Douglas-fir plantations.

The American strain S238N of the ectomycorrhizal fungus Laccaria bicolor (Maire) Orton has been used to inoculate Douglas-fir [Pseudotsuga menziesii (Mir.) Franco] plantations in France over the last two decades. Laccaria fruit bodies are scarce in mature plantations, which precludes further assessment of its persistence by fruit body surveys. Our objective was to develop new markers to identify this strain and its eventual non-fruiting progeny on root tips. We converted nine random amplified polymorphic DNA markers into sequence characterized amplified region (SCAR) markers. Two of these SCAR markers enabled us to detect S238N on roots of seedlings and mature trees. No amplification of non-fungal (host plant, bacterial, etc.) DNA was observed. Moreover, both SCARs were amplified from Laccaria-like mycorrhizas in a Douglas-fir plantation inoculated 14 years ago, demonstrating the long-term persistence of the inoculant strain. We also obtained a SCAR marker to detect one strain of European origin (L. bicolor 81306), indicating that SCARs are potential markers to type the naturally occurring genets. Thus, SCAR markers are of great value in studying the persistence of inoculant strains and the effects on local populations of introducing foreign strains.

Agaricales↗
PubMed2005

Seasonal changes in foliar terpenes indicate suitability of Douglas-fir buds for western spruce budworm.

The terpene composition of current-year buds of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, was analyzed from before budburst to after buds were fully flushed. Terpene composition was measured at weekly intervals for several seasons at eight different locations in the southern interior of British Columbia, Canada. Discriminant functions relating terpene composition to suitability of buds for newly emerged western spruce budworm, Choristoneura occidentalis Freeman, were developed based on terpene profiles of the buds and bioassays measuring the suitability to budworms of a sister group of buds. Changes in percent composition of bud terpenes before and during budburst were closely associated with changes in the suitability of the buds to utilization by budworms at both the tree and site by date levels. Use of a degree-day scale for bud suitability removed much of the year-to-year variation, but remaining differences among sites suggest additional sources of variation influencing the insect host plant relationship. The success of correctly classifying bud suitability using terpene profiles demonstrates the value of foliar terpenes as indicators of seasonal changes in suitability of Douglas-fir foliage during the critical spring emergence period of western spruce budworm. This indicator could be used to screen individual trees susceptible to budworm damage and identify sites at high risk of damaging defoliation.

Animals↗
PubMed1990

CO2/H2O gas exchange parameters of one- and two-year-old needles of spruce and fir.

Gas exchange was characterized in one- and two year-old spruce (Picea abies L. Karst.) and fir seedlings (Abies alba Mill.) which had been exposed to low levels of ozone, sulfur dioxide and simulated rain or a combination of all three variables in open top chambers from 1983 through 1988. The gas exchange measurements were carried out in March 1988 at the end of the five year experiment. The twigs examined did not exhibit any visible sign of injury, specifically no differences were apparent between trees under the treatments of simulated acidic rain at pH 5.0 and pH 4.0. The study of carbon dioxide response curves showed different effects of the pollutants on the tree species. One-Year-old spruce needles treated with O(3) and simulated acidic precipitation pH 4.0 showed noticeable reduction of net photosynthetic rate. Exposure to the combination O(3) and SO(2) at pH 4.0 resulted in a significant depression of photosynthesis in two-year-old needles Transpiration rate was not decreased to a similar extent. No changes either in photosynthesis or transpiration were found in spruce under fumigation with SO(2) alone. These results indicate that ozone is the principal cause of changes in photosynthetic performance of spruce. It alters mesophyll response rather than reducing stomatal conductance. The specific changes that occur in the mesophyll could be diagnosed as inactivation of a carbon fixing enzyme as well as damage of the electron transport system. Fir seem to be more tolerant to ozone. No changes in photosynthesis and transpiration following exposure to O(3) alone were found. However, SO(2) fumigation, alone or in combination with O(3), resulted in a marked decrease of photosynthetic performance. Particularly, carboxylation efficiency and also maximum carboxylation velocity were depressed indicating a reduction in carbon fixing enzyme activity. No differences between single and combined fumigation treatments regarding these variables were determined. However, parameters measured to determine changes in electron transport rate showed a higher depression in the presence of both pollutants. Transpiration also was reduced by SO(2).

Journal Article↗
PubMed1994

Effects of long-term ozone fumigations on growth and gas exchange of Fraser fir seedlings.

Fraser fir seedlings from two seed sources in the Southern Appalachians (Mt Mitchell, North Carolina, a declining population; and Mt Rogers, Virginia, a relatively healthy population) were subjected to long-term (2.5 years) intermittent ozone fumigations (0.025, 0.070, and 0.150 ppm) while being grown through five growth cycles in an accelerated-growing regime. Fumigations took place during bud break, stem elongation and bud set. Following each growing cycle, gas exchange parameters and dry weights were determined. The ozone fumigations did not produce any effect on seedling growth. The ozone fumigation effects on gas exchange parameters were inconsistent, and generally not statistically different, with no differences occurring between seed sources. There was no correlation between photosynthetic rates and seedling growth. These results provide no evidence that ozone may be contributing to the differences in decline noted between the Mt Rogers and Mt Mitchell populations of Fraser fir.

Journal Article↗
PubMed2005

Properties of resorcinol-tannin-formaldehyde copolymer resins prepared from the bark extracts of Taiwan acacia and China fir.

Resorcinol-tannin-formaldehyde copolymer resins (RTF) were prepared by using the bark extracts of Taiwan acacia (Acacia confusa) and China fir (Cunninghamia lanceolata) to substitute part of the resorcinol. From the results, the content of reactive phenolic materials in Taiwan acacia and China fir bark extracts were 51.6% and 46.5%, respectively. Aromatic compounds were the main components in the bark extracts showed by FT-IR analysis. The conventional synthesis condition used for RF resin was certainly not suitable for the RTF copolymer resin. It should be formed the novolak RF prepolymer by reacting the resorcinol with formaldehyde at the first stage, and then the bark extracts added and underwent the copolymerization reaction under acidic condition at the second-stage. The RTF copolymer resins prepared had cold-setting capability. They had higher viscosity, shorter gel time as compared with the RF resin. The RTF copolymer resins could be carried out the gluing application immediately after the hardener was added and had bonding strength the same as RF resin. But the RTF copolymer resins had worse stability and shorter shelf life than RF resin.

Acacia↗
PubMed2005

The influence of climate and soil properties on calcium nutrition and vitality of silver fir (Abies alba Mill.).

As a part of a broader research into the nutrition of silver fir (Abies alba Mill.), the variation of calcium concentrations was investigated in needles and soil in two subsequent, climatologically diverse years. Statistically significant differences between plots were determined in Ca concentrations in soils. Concentrations of Ca in needles were statistically different regarding plot, defoliation class, sampling date within the same year and also between years. Fir trees on acid-rock based soils had lower, often inadequate concentrations of Ca in needles; the opposite was true for trees growing on Ca-rich soils. Trees of lower vitality generally exhibited poor Ca nutrition. Drought in the second year of research caused poor absorption of Ca on all plots and in all defoliation classes, but the combined influence of climate and soil properties affected especially trees of low vitality on acid-rock based soils.

Abies↗
PubMed2005

Genotypic variation and presence of rare genotypes among Douglas-fir tussock moth multicapsid nucleopolyhedrovirus (OpMNPV) isolates in British Columbia.

The Douglas-fir tussock moth (Orgyia pseudotsugata) multicapsid nucleopolyhedrovirus (OpMNPV) is periodically applied to suppress Douglas-fir tussock moth populations in British Columbia and in the western United States. The strain of OpMNPV in the product currently used for suppression is not genetically distinct from naturally occurring OpMNPV. To separate the mortality caused by the applied virus from that caused by the naturally occurring virus, a rare and genetically distinct strain of OpMNPV must be applied. To learn more about the genotypic diversity of OpMNPV populations in BC and to identify rare strains in this region, viral DNA was extracted from larvae reared from 208 field-collected egg masses found in five geographic regions of British Columbia and subjected to REN analysis. Nine, 12, and 9 different genotypes were detected using PstI, SalI, and HindIII, respectively. When the PstI, SalI, and HindIII profiles for each pure (single strain) isolate were grouped and considered as a combined PstI-SalI-HindIII genotype, 23 different genotypes were identified among 185 isolates. Nine rare OpMNPV genotypes were selected as ideal candidates for use as a potential 'marker strain' to accurately determine the efficacy of the treatment.

Animals↗
PubMed2005

Characterization of four terpene synthase cDNAs from methyl jasmonate-induced Douglas-fir, Pseudotsuga menziesii.

Numerous terpenoid compounds are present in copious amounts in the oleoresin produced by conifers, especially following exposure to insect or fungal pests. CDNA clones for many terpene synthases responsible for the biosynthesis of these defense compounds have been recovered from several conifer species. Here, the use of three terpene synthase sequences as heterologous probes for the discovery of related terpene synthase genes in Douglas-fir, Pseudotsuga menziesii (Mirbel) Franco (Pinaceae), is reported. Four full-length terpene synthase cDNAs were recovered from a methyl jasmonate-induced Douglas-fir bark and shoot cDNA library. These clones encode two multi-product monoterpene synthases [a (-)-alpha-pinene/(-)-camphene synthase and a terpinolene synthase] and two single-product sesquiterpene synthases [an (E)-beta-farnesene synthase and a (E)-gamma-bisabolene synthase].

Acetates↗
PubMed2004

Responses of central auditory neurons modeled with finite impulse response (FIR) neural networks.

To simulate central auditory responses to complex sounds, a computational model was implemented. It consists of a multi-scale classification process, and an artificial neural network composed of two modules of finite impulse response (FIR) neural networks connected to a maximum network. Electrical activities of single auditory neurons were recorded at the rat midbrain in response to a repetitive pseudo-random frequency modulated (FM) sound. The multi-scale classification process divides the training dataset into either strong or weak response using a multiple-scale Gaussian filter that based on response probability. Two modules of FIR neural network are then independently trained to model the two types of responses. This caters for the possible differences in neuronal circuitry and transmission delay. Their outputs are connected to a maximum network to generate the final output. After training, we use a different set of FM responses collected from the same neuron to test the performance of the model. Two criteria are adopted for assessment. One measures the matching of the modeled output to the actual output on a point-to-point basis. Another measures the matching of bulk responses between the two. Results show that the proposed model predicts the responses of central auditory neurons satisfactorily.

Action Potentials↗
PubMed2001

Selection effects of air pollution on gene pools of Norway spruce, European silver fir and European beech.

The effects of industrial pollution on allelic and genotypic structures of Norway spruce. European silver fir and European beech were investigated by means of isozyme analysis. In a mixed Norway spruce-silver fir forest stand in an area heavily polluted by sulphur dioxide and heavy metals in the region of Spis (eastern Slovakia), pairs of neighbouring damaged and apparently healthy trees were selected in two replicates (44 and 69 pairs in a heavily and moderately damaged stand, respectively). Pairwise sampling of trees with contrasting vitality was applied to reduce potential effects of site heterogeneity on the vitality of sampled trees. No significant differences in allelic and genotypic frequencies were found between sets of healthy and declining trees. There were differences in the single-locus heterozygosities, but these were not consistent between the replicates. However, the set of damaged trees exhibited higher levels of genetic multiplicity and diversity, possibly due to the deleterious effect of rare alleles under the conditions of air pollution. Consequently. following the decline of pollutant-sensitive trees, the remaining stand will be depleted of a part of alleles with unknown adaptive value to future selection pressures.

Abies↗
PubMed1997

The isolation of a novel metallothionein-related cDNA expressed in somatic and zygotic embryos of Douglas-fir: regulation by ABA, osmoticum, and metal ions.

To isolate genes which are expressed preferentially during embryogenesis, a Douglas-fir embryogenesis cDNA library was constructed and differentially screened with cDNA probes made with mRNA from developing and mature embryos, respectively. The cDNA clone PM 2.1 was isolated based on its abundance in developing seeds and absence in mature seeds, and its predicted amino acid sequence was shown to have structural features characteristic of plant MT-like proteins. Alignment of the PM 2.1 predicted amino acid sequence with other plant MT-like protein sequences revealed a general paucity of Cys and Cys-Xaa-Cys sequences and the presence of novel serine residues within the conserved Cys-Xaa-Cys motifs in the C-terminal domain. The consensus sequence following the Cys-poor spacer in type 2 MT-like proteins, CXCXXXCXCXXCXCX, was modified in PM 2.1 to CXSXXXSXYXX-XCX. Phylogenetic analysis supported PM 2.1 was distinct from other MT and grouped with MT-like proteins from Arabidopsis (OEST), rice (AEST) and kiwifruit (AD1), which do not belong to type 1 or 2. The PM 2.1 gene was expressed in somatic and zygotic embryos, in haploid maternal tissue, as well as in hormone- and metal-treated seeds and seedlings. The PM 2.1 transcripts were detected in the needles of 14-week-old seedlings, but not the root tissue or mature pollen. The expression of the PM 2.1 gene in embryos was dependent upon ABA and osmoticum and in seedlings was differentially modulated by metals, suggesting a role of the PM 2.1 gene product in the control of microelement availability during Douglas-fir seed development and germination. The novel structural features, and the developmental, hormonal and metal modulation of PM 2.1 expression, are evidence for a new type of MT-related protein in plants.

Abscisic Acid↗
PubMed2002

The role of monoterpenes in resistance of Douglas fir to western spruce budworm defoliation.

We conducted defoliation experiments with 7- to 8-year-old clones of Douglas fir [Pseudotsuga menziesii (Mirb.) Franco var. glauca] to assess the role of monoterpenes as a resistance mechanism to western spruce budworm (Choristoneura occidentalis Freeman) defoliation. The grafted clones were derived from mature trees that showed resistance or susceptibility to budworm defoliation in the forest. All clones were exposed to either budworm defoliation or nondefoliation treatments in 1998 and 1999 under greenhouse conditions. We found that the total concentration of monoterpenes in current-year foliage varied greatly between two consecutive years in clones in the greenhouse and in their corresponding mature trees in the forest. Fractional composition of different monoterpenes was similar between different years and between clones and mature trees, indicating genetic control of this trait. Two different defoliation experiments were conducted to assess the importance of budburst phenology as a factor determining host plant resistance. In the 1998 experiment, budworm feeding was matched to the budburst of each individual plant. Monoterpene concentration was high in 1998, and budworm potential fitness was greater on clones from the resistant mature trees that had lower concentrations of total monoterpenes. In the 1999 experiment, budworm feeding was matched to budburst of the whole population of plants in order to mimic conditions similar to insects feeding on trees in the field. The concentration of monoterpenes was low in 1999, and budworm fitness was not related to monoterpenes. Total monoterpene concentration was negatively related to foliar nitrogen concentration, suggesting that C/N balance may affect monoterpene synthesis in needles. However, tree growth was not related to total monoterpene concentration. We concluded that expression of differences in budworm resistance among Douglas fir genotypes might be caused by interactions among multiple resistance mechanisms such as needle monoterpenes and tree budburst phenology.

Animals↗
PubMed2002

Effect of anti-auxins on maturation of embryogenic tissue cultures of Nordmanns fir (Abies nordmanniana).

The present study was conducted to improve the transition from proliferation to maturation in embryogenic cultures of Nordmanns fir. For that reason, chemicals reported to affect endogenous levels or activity of auxin were included in the growth media during maturation. The auxin antagonist PCIB reduced proliferation and promoted the development of numerous high-quality mature embryos in the tested cell lines. PCIB could not substitute for exogenously supplied ABA and the positive effect was only found when PCIB and ABA were used in combination. The effect of PCIB was dependent on the concentration and the application period. The auxin transport inhibitor TIBA also reduced proliferation, but had no positive effect on maturation. The auxin synergist phloroglucinol had the opposite effect of PCIB; proliferation was increased and no maturation was initiated. A lowered concentration of boron had no effect on proliferation but had some positive effect on maturation. The optimum protocol for PCIB application was strongly genotype dependent, and a general scheme that covered the tested cell lines could not be found. Overexposure to PCIB during maturation caused abnormal development of the mature embryos, which was revealed by a reduced number of cotyledons. These results suggest that endogenously produced auxin may be one reason for low or failing maturation of embryogenic cultures of Nordmanns fir, but also imply that auxin may play a critical role for proper development of cotyledons during the later stages of embryo maturation.

Journal Article↗
PubMed1996

Abietadiene synthase from grand fir (Abies grandis). cDNA isolation, characterization, and bacterial expression of a bifunctional diterpene cyclase involved in resin acid biosynthesis.

(-)-Abietic acid, the principal diterpenoid resin acid of the wound-induced oleoresin secreted by grand fir (Abies grandis), is synthesized by the cyclization of geranylgeranyl diphosphate to (-)-abieta-7(8),13(14)-diene, followed by sequential three-step oxidation of the C-18 methyl group of the olefin to a carboxyl function. The enzyme catalyzing the cyclization reaction, abietadiene synthase, was purified from stems of wounded grand fir saplings and was digested with trypsin. Amino acid sequence information from the resulting peptides allowed construction of degenerate oligonucleotide primers, which amplified a 551-base pair fragment from a wound-induced stem cDNA library. This hybridization probe was then utilized to screen the wound-induced stem cDNA library, from which three cDNA clones were isolated that were functionally expressed in Escherichia coli, thereby confirming that a single protein catalyzes the complex, multistep cyclization of geranylgeranyl diphosphate to abietadiene. cDNA isolate Ac22.1, which yielded the highest expressed level of cyclase activity, was 2861 base pairs in length and encoded an 868-amino acid open reading frame that included a putative plastidial transit peptide. Deduced amino acid sequence comparison to other terpene cyclases revealed an amino-terminal region of the abietadiene synthase, which resembles those of enzymes that employ substrate double bond protonation to initiate the carbocationic reaction cascade, and a carboxyl-terminal region of the synthase, which resembles those of enzymes that employ ionization of the substrate allylic diphosphate ester function to initiate the cyclization reaction. This apparent fusion of segments of the two distinct terpenoid cyclase types is consistent with the novel mechanism of the bifunctional abietadiene synthase in catalyzing both protonation-initiated and ionization-initiated cyclization steps.

Abietanes↗
PubMed2000

Morphology and Stomatal Function of Douglas Fir Needles Exposed to Climate Change: Elevated CO2 and Temperature.

Climate change may have an impact on the productivity of conifer trees by influencing the morphology (size and surface characteristics) and function (capacity for gas exchange) of conifer needles. In order to test the responses of needles to climatic variables, Douglas fir (Pseudotsuga menziesii [Mirb.] Franco), saplings were grown in sunlit controlled environment chambers at ambient or elevated (+200 parts per million above ambient) CO2 and at ambient or elevated temperature (+4 degrees C above ambient). Needle characteristics, including length, width, area, stomatal density (stomata per mm2), percentage of stomatal occlusion, and the morphology of epicuticular wax, were evaluated. Needle function was evaluated as stomatal conductance to water vapor and transpiration. Needle length increased significantly with elevated temperature but not with elevated CO2. Neither elevated CO2 nor elevated temperature affected stomatal density or stomatal number in these hypostomatous needles. Epicuticular wax was less finely granular at elevated than at ambient temperature and was similar in appearance at elevated and ambient CO2. Stomatal conductance and transpiration increased with elevated temperature and associated increased vapor pressure deficit; however, neither conductance nor transpiration was affected by elevated CO2. These results indicate that simulated climate change influences Douglas fir needle structure and function.

Journal Article↗